What problems are prone to occur during welding of 316L stainless steel plates?

　　316L stainless steel plate is prone to the following problems during welding:

　　l Hot cracks: Because 316L stainless steel contains more metal elements such as Cr and Ni, it is easy to form low melting point compounds or segregation of eutectic boron and silicon with impurities such as S and P, which will promote hot cracks; welds are easy to form directionality The strong and coarse columnar crystal structure is conducive to the segregation of harmful impurities and elements, and then promotes the formation of a continuous intercrystalline liquid film, which improves the sensitivity of thermal cracks; if the heating is uneven during welding, it is easy to form a large tensile stress. Promote the occurrence of welding thermal cracks.

　　l Intergranular corrosion: According to the chromium-deficient theory, when the weld seam and the heat-affected zone are heated to the sensitization temperature range of 450-850°C, sensitization will occur, and the supersaturated solid solution carbon will loosen the distance from the grain and the grain boundary The chromium structure forms chromium carbide (CrFe) 23C6, and accumulates at the grain boundary. The loosening rate of chromium atoms is not as fast as that of carbon, and it is too late to replenish from the grain to the vicinity of the grain boundary. Therefore, a chromium-poor area appears in the grain boundary, and the anti-corrosion function is lost. Intergranular corrosion will occur after working in a corrosive medium for a period of time.

　　In order to effectively control the above problems during welding of 316L stainless steel plates, in addition to selecting suitable welding consumables, the selection of reasonable welding techniques is the key. When welding, the energy-concentrated welding method should be adopted, a smaller current, a faster welding speed should be selected, heat input should be reduced, the cooling speed of the weld seam should be accelerated, and the cooling time for passing through the dangerous temperature zone should be shortened.